1. Field of the Invention
The present invention relates generally to a user terminal for a videotex system and, more particularly, is directed to a user terminal capable of displaying picture information in an off-line mode.
2. Description of the Prior Art
Recently, in Japan, a videotex system, which is referred to as CAPTAIN (character and pattern telephone access information network) system, has been started which offers commercially available service. The CAPTAIN system has such significant features as the ability to use an existing telephone network line as a transmission line and to use a home television receiver as a display apparatus for displaying character and figure or pattern information sent over the telephone line. Since this videotex system carries out a conversational (i.e. interactive) type communication, it has a wide field of application.
In order for a user to retrieve the requested information, the user has to operate a keyboard to access a menu picture stored at the center computer and, while checking the menu picture, the user has to repeat a number of keyboard operations. The more frequently the keys are operated, the more frequently mistakes occur in the key operation. This causes unnecessary information to be retrieved and requires an error correction operation, etc. Large losses from a time and economical standpoint can result. The above mentioned problems become more serious when a picture of restricted range is repeatedly utilized, as in a sales promotion and in education. In addition, since the transmission bit rate is relatively low, it takes a lot of time for the user to reach the desired information. During this long retrieval operation period, the user terminal and the center computer are connected through a telephone network line, requiring a large communication charge. For example, when the user does a study program by utilizing educational information accumulated in the CAPTAIN system, the user reaches the first question picture in accordance with the afore-mentioned procedures. Then, the user operates the keys to choose the selection branch that the user thinks is correct. If it is the correct answer, the next question picture is displayed on the receiver. If on the other hand the selection branch is not the correct answer, the fact that the answer is not correct is displayed on the next picture and the user comes back to the preceding picture. Then, the user selects the correct answer branch. Through similar operations, the user reaches the final question picture. In this case, the time required by the user to answer the problem is also included in the communication time so that the communication charge amounts to a large sum.
In the case of a sales promotion, various kinds of sales promotion information concerning consumer goods (catalog goods) such as expensive goods and made-to-order goods that a general retail shop can not always store as stock are conventionally distributed in the form of a printed article from a manufacturer to respective retail shops, including the market prices that are changed freely. This inefficient distribution of information can be avoided by furnishing it electronically as a picture of the CAPTAIN system. Using the CAPTAIN system, the retail shop can freely obtain the latest sales promotion information for various kinds of catalog goods without loss and trouble.
In the sale of catalog goods, a medium, for example an optical video disc, on which a picture of the catalog goods is recorded, is distributed to the retail shops. In a retail shop, the business talk goes on with customers who are seeing the picture reproduced from the video disc. In order to synchronize the up-to-date sales promotion information concerning the particular goods, which information is supplied over the telephone line from the CAPTAIN system, with the reproduced picture from the user terminal's video disc corresponding to the same goods, it is necessary that control information to control the video disc reproducing apparatus (or any other peripheral apparatus) be simultaneously sent to the user terminal as tele-soft information. This enables the latest sales promotion information of various kinds of catalog goods to be freely reproduced together with the catalog information stored on the video disc and effectively utilized for the sales activities of the retail shop.
However, when the sales promotion information according to the above mentioned CAPTAIN system is utilized, it takes a lot of time to reach a desired picture and also there is a high probability that misoperation will occur. The sales promotion information concerning the same catalog goods is reproduced each time when the business talk is made with different customers. Moreover, the greater the number of customers, the more serious the time and communication charge problems become.
A fundamental problem in all of these examples is that the tree information for controlling the retrieval of the desired picture is stored in the memory of the center computer and is not transmitted to the user terminal. The succeeding picture information to guide the user is also stored in the memory of the center computer and is not sent to the user terminal. That is, the user terminal can receive only the picture information to be displayed on a screen of the television receiver and not the menus program itself.